Annular fuel vaporizer for gas turbine engines



July 28, 1953 R. s. MESCHINO ANNULAR FUEL VAPORIZEIR FOR GAS TURBINE ENGINES 2 Sheets-Sheet 1 Filed Feb. 18, 1950 INVENTOE IEQ/VfSCH/NO Wfl July 28, 1953 R. e. MESCHINO ,66

ANNULAR FUEL VAPORIZER FOR GAS TURBINE ENGINES Filed Feb. 18, 1950 2 Sheets-Sheet 2 q: nw/z/vro/e e a. mrscm/vo 407 T ORNE X the combustion chambers into a turbine.

Patented July 28, 1953 ANNULAR FUEL VAPORIZER FOR GAS TURBINE ENGINES Ronald Guerin Meschino, Toronto, Ontario, Canada, assignor to A. V. Roe Canada Limited, ntario, Canada, a corporation Application February 18, 1950, Serial No. 145,060 In Great Britain February 24, 1949 Claims. 1 r This invention relates to vapourizing systems for the combustion chambers of gas turbine engines.

Those skilled in the art will be familiar with the principles of operation of a gas turbine engine wherein fuel is burned in a high pressure,

high velocity air stream and discharged from Combustion actually takes place within a liner (also known in the art as a flame tube) situated inside the combustion chamber and in spaced relationship to the walls thereof, so that the liner is in effect jacketted by a stream of air which is progressively admitted to the liner to support combustion and to provide a working medium. Combustion is initiated at the upstream end of the liner by the introduction of fuel to a limited supply of primary air in a region of reverse flow, so that once started by an electric spark or some similar means, the flame becomes self-propagating.

Fuel may be introduced into the liners of combustion chambers of gas turbine engines either by means of an atomizing spray, in the form of .vapour or as a rich mixture of vapour and air.

In the last-mentioned case, liquid fuel and a supply of air are introduced into special vapourizing elements exposed externally to the heat of combustion so that the fuel passing through them is vapourized before it is discharged into the flame zone. In the past these vapourizing ielements usually have been tubes extending directly into the flame zone, but it has been found difficult to distribute the fuel evenly over the internal surfaces of these tubes and since in the process of vapourizing, the fuel serves to cool the tubes, this uneven distribution has resulted in many tube failures due to excessive local heating. Furthermore, local heating has been aggravated by the deposition of carbon upon the external surfaces of the vapourizer tubes, necessitating such precaution as the provision of a film of insulating air over the said surfaces; but such complications have not proved to be completely eifective.

The principal object of this invention is to provide a vapourizing element for a combustion -detached and being carried downstream to do serious damange to the turbine.

Another object is to eliminate the likelihood'of cracking of the fuel due to contact with high tempera- Qtrire surfaces, with its attendant gumming effects. Yet another object is to provide a vaand the liner.

pourizing element which is easy and cheap to manufacture, being of simple configuration and robust construction.

Further objects and advantages of the invention will be apparent from the following description of an application of the invention to a combustion system of the annular type. It will be understood, of course, that the invention can be similarly applied to combustion systems having tube type combustion chambers and that this description of a preferred construction is not to be taken as restrictive to any particular arrangement.

In the accompanying drawings forming a part of this application and in which like characters of reference are used to designate like parts throughout the same:

Fig. '1 is a view in side elevation, partly broken away, of a gas turbine engine embodying an annular combustion system constructed according to this invention;

Fig. 2 is a cross-sectional view of the annular combustion system of the engine, the said view being taken on the line 22 of Fig. 1; and

Fig. 3 is a cut-away perspective view of the said annular combustion system.

In the operation of the engine shown in Fig. 1 air is compressed in a compressor l0 and fed into a combustion system H through a diffuser l3. Fuel is injected into the combustion system and burnt in the stream of air, and the products of combustion are discharged at high velocity into a turbine l4, which drives the compressor and, according to the construction of the turbine, otherwise generates power from the energy contained in the hot gases. The final discharge of the gases from an exhaust I5 may be employed for jet propulsion of the unit.

The combustion system comprises an annular combustion chamber bounded by an inner wall I6 and an outer wall I! arranged coaxially with the usual backbone member l8 of the engine. Between the walls [6 and I! is the combustion chamber liner or flame tube having an inner wall 20 and an outer wall 2|; these walls are supported in spaced relationship to the walls of the combustion chamber so that there are annular spaces 22 and 23 between the inner and outer walls, respectively, of the combustion chamber The annular entry to the'fiame tube, between the inner and outer wall 20 and 2|, is divided into two concentric annuli by a wall 24'. This wall, as shown in Fig. 3, runs substantially parallel to the inner wall 20 and extends downstream for a short distance, defining, with the wall 20, an annular space 25 which constitutes the inner of the two concentric annuli'mentioned above;

at the upstream end of the annulus 25 are a number of swirl vanes 26 circumferentially spaced around the annulus to induce swirl to the air entering the said space. The Outer of the two, concentric annuli, which is the principal entry into the liner, is also traversed by a series of circumferentially spaced swirl vanes 263, extending between the outer wall 2! and the wall 24. V

Spaced downstream of the end of the wall 24 is a transverse annular baffle 23, mounted on th inner wall 20 of the liner andcarryins on its noriphery, remote from the said wall 20, a 91:- wardly extending flange 28 which overlaps the terminal portion of the wall '24' of substantially greater diameter than the said overlapped portion of the wall.

Fuel is introduced through a manifold 29 and a plurality of .circumierentially spaced Jets 3% situated in the space '25 immediately downstream of the swirl yanes 25. The Jets .39 are arranged to inject fuel tangentially into the space 25 in the same sense as the swirl induced in th air by the said vanes.

In accordance with normal practice relating to combustion chamber liners the inner and outer walls 2,0 and p21 are perforated at intervals along their length tdownstream of the heme 21 by e .number of holes 32 and 13 for the progressive admission of air from the spaces 22 and 123 between the walls of the liner and the -combustion chamber, as will be explained hereunder.

In operation, air f om the compressor en rs the combustion system in the direction of the arrows hand a portion of the stream i re i al ne the annular spaces 2.2 and 23 forming a Jacket of comparatively cold .air around th lin r- Another portion of the entering a S direc e into the .annular spaoe- ,25, between the swirl Ynnesifi, and the remainder enters the upstream end. of the combustion chamber liner between the swirl Manes 25 which impart a rotary motion to the air passing over them, as indicated by the arrows 3.; thu th vair enters the i e -.a helical stream and the centrifugal forces acting :theneupon .cause the air to flow along the outer wall ,2] as indicated by the arrows C an :n v de a c rrespondin e o of low p sure adjacent the wall 24.

Liquid iuelisiniected through theists 139 into t stream of air fl win through the annula space v25 and because .of the tan ential direction of this-injection and the swirlimnarted "to the .airstream .bylthe vanes 26,.the fuel is cai riedout ward by centrifugalaction until itimpinges upon the .innersurface of the wall 24. I11 mixture of fuelan-dairthuspassing throush th annular space :25 .is turned through approximately 180 .by the baifleil audits flange 18,.50 thatthe fuelair imixtureremerges into the .low pressure region of the flame zone within the liner, along the outer surfaceof the wall 2A,,in .the direction of the-arrows D.

The main flow of air entering the flame tube in .the direction of the arrows C and the .fiOW .of rich iueleair ,mixture entering in ,the direction of the arrows D together generate ;a toroidal vortex Ein th region of llow pressure between them. This rtor id l' vortex extends en irely around, the !annulus of the liner .and, .in ,it, a

. rthor us rm sinelo the two stre ms isaoh er d;

*thGyVGItE-X; forms gtheieore of ithe combustion taking place-"in rth liner :and, as its sn iph at l r-m nts san rcontinu ly arrieddownstream u :the =ai -1is:.edde :throush the 1101 5 3.2 iix3 to support combustion and provide the working fluid for the turbine. Once lighted, the combustion in the vortex is self-propagating.

The wall 24 isdirectly exposed to the combustion in the vortex and becomes, in consequence, very hot. Deterioration of the wall 24, which such high temperatures would normally cause, is prevented by the cooling effect of the fuel being sprayed by the jets onto its inner surface and bythe additional influence of the air stream in the annular space 25. In cooling the wall the fu e l is itself vapourized and the air-vapour mix ture is heated, sov that the gases emerging into the combustion zone of the liner are in a suitable condition for combustion. The vapourizing surface of the wall 24 is so extensive in comparison with the surface available in tube type Vapourizer installations that it can achieve more complete vapourization at a lower temperature, thereby, eliminating gumming and carbondeposition, improving combustion and enhancing the life of the -v apourizer element. Further more since vapourization is complete there is no tendency to centrifugal separation of the fuel from the air as the flow of mixture is reversed by the 'baflie 21.

In the foregoing description the terms inner, outer and the like have been used in reference to the longitudinal axis of the engine; for example, the inner wall of the "liner is of lesser diameter than the outer wall thereof. However, such expressions as within the combustion chamber; internally to the flame tube and the like have been used in the sense that the coinbustion chamber and its liner are substantially enclosed chambers or conduits, regardless of their external conf guration; for example, the expression fwithin the flame tube in an anmilar sys tem, as described, would signify external to the inner wall and internal to the outer wall of the annulus, whereas in a tube type system it would signify simply surrounded by the wall of the tube. Such adverbial phrases may be applied generically to both annular and tube type combustion systems and are so used in thesubjoined I t will be understood that the above descriptionhas included certain features peculiar to an annular typecombustionsystem and thatin applying the invention to a tube type combustion system advantage cannot be taken of centrifugal efiects in directing the flow of fuel and gases;

furthermore, in someannular type systems, in

t ki slthe or h s d ub W l e e dinslo ,the whole or a partof the'liner, around the flame .zone (the i u e a b t e inside t llner as herein described, or outside the' liner) andthis fea ur may eappli d w th. van g to a ty o vt n is- .1sti ch be t d elo a vortex core and an improv ed flame pattern .mien.t ws wtcmnm n yi p o i g at h same tim a cheapl manufa tur a ro u wapourizer unctionin a c mparat e Q tem eratures and-virtual elimin ting l s- ..certibi. ity..to loca o erheat n The application of the invention herein shown and described is to be taken therefore as a preferrd example of the same and various changes in the shape, size, and arrangement of the parts may be resorted to, without departing from the spirit of the invention or the scope of the claims.

What I claim as my invention is:

1. A vapourizing system for a gas turbine engine embodying a combustion chamber through which a stream of air is caused to flow and a liner having open ends to receive part of the air and disposed substantially coaxially within the combustion chamber, comprising, a wall spaced from a wall of the liner and defining with the said liner wall an annular vapourizing space extending downstream substantially from the upstream end of the liner, an inlet in the said space for directing a portion of the air entering the liner into the upstream end of the said space, means for introducing fuel into the said space for conversion to fuel vapour, and a flow reversing surface extending into the flow path of the fuel vapour emerging from the downstream end of the said space into the liner whereby the fuel vapour is directed upstream.

2. A vapourizing system for a gas turbine engine embodying a combustion chamber through which a stream of air is caused to flow and a liner having open ends to receive a part of the air and disposed within and spaced from the combustion chamber, comprising, a wall disposed coaxially within and spaced from the liner and extending downstream substantially from the upstream end of the liner, the said wall with the liner defining an annular vapourizing space open at the upstream end for directing a portion of the stream of air into the said space, means for introducing fuel into the said space for conversion to fuel vapour, and a flow reversing surface extending into the flow path of the fuel vapour emerging from the downstream end of the said space into the liner whereby the fuel vapour is directed upstream.

3. A vapourizing system for a gas turbine engine as claimed in claim 2 in which the said flowreversing surface is provided by an annular baffle disposed transversely of the liner downstream of.

the said wall.

4. A vapourizing system for a gas turbine engine as claimed in claim 2 in which said flowreversing surface is provided by an annular baffle disposed transversely of the liner, the said bafiie being in concentric spaced relationship to the downstream end of the said annular space and being provided with a flange extending upstream.

5. A vapourizing system for a gas turbine engine as claimed in claim 2, in which the fuel introducing means includes a plurality of jets situated within the said annular space adjacent the upstream end thereof.

6. A vapourizing system for a gas turbine engine embodying a combustion chamber through which a stream of air is constrained to flow and a liner having open ends to receive part of the stream of air and disposed substantially coaxially within the combustion chamber, comprising an annular vapourizing element coaxial with the liner and extending downstream substantially from the upstream end thereof, an inlet in the vapourizing element for directing a portion of the air entering the liner into the upstream end of the vapourizing element, means for introducing fuel into the vapourizing element, a baffle disposed adjacent the downstream end of the vapourizing element and extending into the flow path of said portion of the air stream and the fuel emerging from the downstream end of the vapourizing element into the liner whereby the air and fuel emerging from the said element are directed substantially upstream, and means at the upstream end of the liner for imparting a swirl to the remaining portion of the air entering the liner.

7. A vapourizing system for a gas turbine engine embodying a combustion chamber through which a stream of air is constrained to flow and a liner having open ends to receive part of the stream of air and disposed substantially coaxially within the combustion chamber comprising, an annular vapouriz-ing element substantially coaxial with the liner and extending downstream substantially from the upstream end thereof, an inlet in the vapourizing element for directing a portion of the air entering the liner into the upstream end of the vapourizing element, means in the vapourizing element for imparting a swirl to the said portion of the air, means for introducing fuel into the vapourizing element, and means for reversin the flow of the said portion of the air stream and the fuel as they emerge from the downstream end of the vapourizing element into the liner whereby the air and fuel emerging from the said element are directed substantially upstream.

8. A vapourizing system for a gas turbine engine as claimed in claim 7 in which the said swirl imparting means comp-rises a plurality of swirl vanes in the inlet of the vapourizing element.

9. A vapourizing system for a gas turbine engine as claimed in claim 7 in which the means in the Vapourizing element for imparting a swirl to the said portion of the air comprises a plurality of swirl vanes in the inlet of the vapourizing element, and in which means are also provided at the upstream end of the liner for imparting a swirl to the remaining portion of the air entering the liner.

10. A vapourizing system for a gas turbine engine embodying a combustion chamber through v which a stream of air is constrained to flow and a liner having open ends to receive part of the stream of air and disposed substantially coaxially within the combustion chamber comprising, a wall disposed coaxially with respect to the liner in spaced relationship thereto and extending downstream substantially from the upstream end of the liner, the said wall with the liner defining an annular spaced adapted to receive a portion of the air entering the flame tube, a plurality of swirl vanes disposed at the upstream end of the annular space for imparting a swirl to the said portion of the air, means for introducing fuel into the annular space, an annular baffie mounted transversely of the liner and in concentric spaced relationship to the downstream end of the said wall, and a flange on the baflie extending upstream beyond the downstream end of the wall and spaced therefrom.

RONALD GUERIN lVl'ElSCI-IINO.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,278,499 Esnault-Pelterie Sept. 10, 1918 2,471,892 Price May 31, 1949 2,475,911 Nathan July 12, 1949 2,498,728 Way Feb. 28, 1950 2,541,900 Williams Feb. 13, 1951 2,546,432 Darling Mar. 27, 1951 2,552,851 Gist May 15, 1951 

